Permeable Interlocking Concrete Pavers (PICP) are a relatively new type of Sustainable Urban Drainage System treatment technology that has become increasingly popular in recent years to mitigate the consequences urbanisation such as increased stormwater runoff volumes and pollution loads, increased riskof downstream flooding and increased heat island effects. In Germany, PICPs have suffered damage due to severe climatic conditions over the last fewdecades and new regulations have now been introduced to minimise future damage. The new regulations stipulate that PICPs with porous top surfaces may no longer be used and stormwater must now be infiltrated through the joints between PICP pavers. In addition, new German guidelines have been introduced that specify the type of materials allowed to fill the joints of PICPs. This paper describes and presents the results of an experimental investigation that was undertaken on six different PICP structures to evaluate the hydraulic behaviour and determine the most effective joint filling and bedding materials for PICP systems in Germany.